Despite recent advance in antibiotic therapy and intensive care, sepsis remains the most common cause of death in the intensive care units, claiming > 225,000 victims annually in the U.S. alone. Its pathogenesis is partly attributable to dys-regulated inflammatory responses that are propagated by early proinflammatory cytokines (e.g., TNF and IFN-gamma) but sustained by late-acting proinflammatory mediators (e.g., HMGB1). Agents targeting early proinflammatory cytokines (e.g., TNF) could be protective if given prophylatically; whereas agents capable of inhibiting HMGB1 release or activities could rescue animals from lethal sepsis even if given after onset of disease. Our seminal discovery of HMGB1 as a late mediator of lethal sepsis has prompted further investigation for developing new experimental therapeutics. We have generated preliminary data indicating that major components of several commonly used Chinese herbs, Danshen (Salvia miltiorrhiza, steroid-like tanshinones) and Green tea (Camellia sinensis, epigallocatechin gallate, EGCG) effectively attenuated endotoxin-induced HMGB1 release, and improved animal survival in murine models of endotoxemia and sepsis when given intraperitoneally. However, it is not known whether and how herbal components, individually or in combination, affect HMGB1 release induced by other inflammatory stimuli (e.g., G+ bacterial exotoxin, CpG-DNA, TNF, or IFN-gamma), and consequently influence the outcome of lethal endotoxemia and sepsis if given via clinically feasible (intravenous or oral) route of administration. The experiments outlined in Aim 1 will test the hypothesis that herbal components affect HMGB1 release induced by other exogenous (e.g., G+ exotoxin or CpG-DNA) or endogenous (e.g., TNF or IFN-gamma) stimuli, and that herbal components divergently influence HMGB1-induced release of nitric oxide, chemokines, and growth factors. In Aim 2, we will test a novel hypothesis that herbal components inhibit HMGB1 release either by facilitating endocytic re-uptake (recycling) of extracellular HMGB1, or by stimulating autophagic HMGB1 degradation. The experiments outlined in Aim 3 will test the hypothesis that oral or intravenous administration of herbal components protects animals against lethal endotoxemia and sepsis by modulating peritoneal leukocyte infiltration, systemic and peritoneal inflammation, tissue injury, and organ dysfunction. Answers to these questions will significantly improve our understanding of immune modulatory mechanisms of two commonly used Chinese medicinal herbs, and shed light on the development of alternative strategies for treatment of sepsis and other inflammatory diseases. PUBLIC HEALTH RELEVANCE: Sepsis remains the most common cause of death in the intensive care units, claiming > 225,000 victims annually in the U.S. alone. It is a multi-factorial disorder that triggers an uncontrolled systemic inflammatory response, ultimately leading to multiple organ failure and death. Our recent discovery of HMGB1 as a late mediator of experimental sepsis has prompted investigation of Chinese medicinal herbs as potential HMGB1- targeting therapeutic agents. The long-term goal of this application is to elucidate novel mechanisms by which major components of two medicinal herbs [Danshen (Salvia miltiorrhiza) and Green tea (Camellia sinensis)] inhibit HMGB1 release, and consequently protect animals against lethal endotoxemia and sepsis.